Fire control mechanism



Aug. 18, 1953 A. F. GAIDOS FIRE CONTROL MECHANISM 4 Sheets-Sheet l Filed Oct. 16, 1947 Alunzu E Efiidua IN V EN TOR.

Aug. 18, 1953 A. F. GAIDOS 2,649,031

FIRE CONTROL MECHANISM F'iled Oct. 16, 1947 4 Sheets-Sheet 2 IEELQHB- INVENTOR.

Aug. 18, 1953 A. F. GAIDOS FIRE CONTROL MECHANISM 4 Sheet's-Sheet 5 I INVENTOR. 63 e4 Alunzu F Eaidua A 6/ Aug. 18, 1953 A. F. GAIDOS 2,649,031

FIRE CONTROL MECHANISM Filed Oct. 16, 1947 4 Sheets-Sheet 4 Alunzu .F. Bailing I I INVENTOR.

Patented Aug. 18, 1953 UNHTED STATES PA'EE'E' 13 Claims.

This invention relates to improvements in fire control mechanisms and has for its primary purpose to provide means to convert a semi-automatic firearm which is capable of only being fired one shot for each pull of the trigger, to a fully-automatic firearm capable of being fired one or a plurality of shots for each pull of the trigger, with firing to continue until the trigger is released or the contents of the ammunition magazine have been exhausted.

Another object of my invention is to provide means to convert a semi-automatic firearm into a fully-automatic firearm without the necessity of altering or modifying any of its existing metal components, either by hand operations or by means of machine tools.

Another object of my invention is to provide means whereby a semi-automatic firearm may be converted into a fully-automatic firearm without disturbing the basic arrangement of its existing parts, nor disturbing the original functions of the various mechanical parts employed in the basic mechanism.

Still another object of my invention is to provide simplicity in fabricating the various parts employed in the conversion since, in my invention I provide a means to eliminate the necessity of maintaining extremely close tolerances in the fabrication of the various components, due to the adjustable features employed in the design of the actuating mechanism of the invention, which may be adjusted to suit the dimensions of the existing operating slide of the firearm upon which depends, in this instance, the satisfactory operation of the firearm.

Specifically, my invention provides for the conversion of semi-automatic firearms by means of supplementing the existing parts of a semiautomatic firearm with certain simple mechanical components essential to accomplish either semi-automatic or fully-automatic operation of the firearm by selective control at the will of the firer.

I desire to draw attention to the fact that semi-automatic firearms such as the one illustrated in U. S. Patent No. 2,308,283, granted January 12, 1943, on an application of T. L. Humeston, filed September 22, 1941, and known as the U. S. carbine, caliber .30 M1, for example,

which as originally designed and produced in great quantities for military use, is capable of only delivering one shot for each pull of the trigger. However, due to the present-day demand by the armies of all nations for increased firepower, it has become necessary to place into manufacture newly designed firearms having incorporated in them features by which the firearm may, by selective means, be employed either as a semi-automatic firearm or a fully-automatic firearm. In the case of the U. S. carbine, caliber .30 M1 of which this country has enormous quantities on hand, it would, by means of my invention, be possible to convert every one of these firearms at very little expense, into firearms which could, by selective means, be employed as semi-automatic or fully-automatic firearms, without the necessity of performing any machining operations on any of their metallic components. I also desire to point out the fact that while there are in existence several conversion means for this particular firearm, these means necessitate major machining operations on several major parts as well as so-called doctoring some of its existing parts in order to accomplish the desired result. I also desire to point out the fact that any conversion means which necessitates re-machining or doctoring some of the existing major components is not to be considered a desirable solution to the problem, for the reason that when a precision mechanism such as employed in firearms is once modified or altered, interchangeability of parts, which is essential in any military firearm, is entirely destroyed and the process of fabricating parts becomes complicated and the cost prohibitive.

My invention permits conversion vice versa in a matter ofa few minutes without the aid of tools, merely by adding or removing the components comprising my invention to or from the parts originally employed in the operating mechanism of the firearm.

While not limited thereto, my invention is particularly applied to semi-automatic firearms of the type employing reciprocating slides operated by the conventional-type gas-piston to function the bolt between its loaded battery position and unlocked, recoil position in a manner clearly understood by those familiar with the art.

The invention to be described in greater detail is a selective fire converter essentially comprising a bracket member mountable on the trigger housing of the firearm by utilizing existing transverse pin holes in the trigger housing for proper fastening and aligning of the bracket, a sear tripping member movably mounted on said bracket and being capable of being properly positioned by the trigger of the firearm to enable it to trip the sear and release the hammer when the trigger is pulled, an actuating member capable of being adjusted to suit the length of the operating rod on which depends the functioning of the weapon and a selector mechanism which positions the actuating member for the type of fire desired.

The specific nature of the invention as well as other objects and advantages thereof will be clearly understood from the description of the preferred embodiment as shown in the accompanying drawings, in which:

Fig. 1 is a fragmentary exterior view of the action of a firearm typical of the one to which my invention is applicable.

Fig. 2 is an exterior view of the firearm.

Fig. 3 is a fragmentary cross-section of the action of a typical firearm showing the fire control parts in normal position prior to the commencement of the operating cycle.

Fig. 4 is a fragmentary cross-section showin the position of the parts in the first stage of the operating cycle.

Fig. 5 is a fragmentary cross-section showing the position of the parts in the second stage of the operating cycle.

Fig. 6 is a fragmentary cross-section showing the position of the parts in the third stage of the operating cycle.

Fig. 7 is a fragmentary cross-section showing the positions of the various parts at the instant bolt has reached battery position with trigger still remaining in the pulled position.

Fig. 3 is a top view of the trigger housing in a typical firearm taken on line 88 of Fig. '7.

Fig. 9 is a perspective view of the parts combining the bracket and sear-tripper employed in my invention.

Fig. 10 is a perspective view of the parts combining the selector lever and mounting-plate of my invention.

Fig. 11 is a side view of the adjustable actuator member employed in my invention.

Fig. 12 is a fragmentary top view of the actuator member showin the pawl mounting, taken on line |2-i2 of Fig. 11.

Fig. 13 is a fragmentary side view of a typical firearm showing all components combining my invention in relative positions.

Fig. 14 is a partial top view of the actuator member on firearms showing the adjustment features.

Fig. 15 is a fragmentary cross-section of the trigger mechanism showing the position of the sear-tripper when the trigger is in unpulled non-firing position and bolt in locked battery position.

Fig. 16 is a fragmentary cross-section of the trigger mechanism showing the position of the sear-tripper when the trigger is in pulled or firing position and bolt in unlocked recoil position.

In Fig. 1 there is shown in assembled relation a typical firearm of the semi-automatic type embodying this invention. The major elements of such firearm are identical to the U. S. carbine, .30 M1, which as is commonly known is constructed to fire semi-automatically. Such firearm comprises, mainly, a receiver I, a barrel 2, a bolt 3, and trigger housing 3. Barrel 2 is threadably united to receiver i at A and oppositely disposed guides '5, provided on the rear portion of the trigger housing t engage corresponding ways 3 formed in the rear end of receiver I. The forward end of trigger housing 4 is secured to the receiver I by a transverse headed pin l. Bolt 3 is horizontally mounted in receiver I and reciprocates therein in suitable horizontal ways provided within the receiver. On the underside of barrel 2 there is slidably mounted an operating slide 8 and such slide is connected to the bolt 3 by the rearwardly projecting off-set handle 9. The slide 8 receives the blow from the conventional type piston actuated by gas escaping through a port in the underside of the barrel in a manner known to those familiar with the art; the blow initiating the firing cycle. However, in order to thoroughly understand the operation of the various parts in the fire control mechanism during the complete operating cycle, I refer to Fig. 3, wherein is shown all parts common to the U. S. carbine, caliber .30 M1 in their relative positions at the moment of desire to fire the initial shot to initiate the firing cycle. It will be noted that hammer l3, journalled on a transverse pin I 2, is under bias of hammer strut l3, urged forward by a compression spring l4 mounted on the cylindrical stem I5 of the strut l3. Withinv the trigger housing 4 are contained the trigger l6, and sear ll, both journalled on a transverse pin IS, the ends of which are secured in oppositely disposed walls 19 of the trigger housing 4. In lieu of a cylindrical hole in sear ll as is provided in trigger Hi, there is provided an elongated hole 23 for the purpose of permitting the sear I! to fioat-to-andfro within the confines of the contour of the hole. Sear I1 is under bias of spring 2|, one end of which abuts the end of hole 22 of trigger I6, the other abutting a recess 23 of sear l1. Trigger I6 is continually under bias of a torsional-type spring 24 housed in an aperture 25 of housing 4. The function of spring 24 is to continually urge the heel 26 of trigger I 6 toward its seat 2'! in the trigger housing 4'. A semi-circular are 28 formed on bottom portion of hammer I0 terminates in a step or notch 28a and serves to receive nose 29 of sear I! when the angular position of the notch 28a. is in juxtaposition with nose 29. for the purpose of blocking hammer 10.

It will be noted that when bolt 3 commences its recoil movement the surface 30 of bolt 3 comes into contact with surface 3| of hammer ID and rotates it clockwise on its transverse pin 12 with the limit of rotation governed by the distance from bottom surface 32 of bolt 3 and top surface 33 of hammer 10 (Fig. 4). It will also be noted that bolt 3, during recoil overrides hammer iii and swings it so that notch 28a is swung somewhat beyond the position of the nose 29 of scar I1 to enable the nose of scar, under bias of spring 2| to jump upward into notch 28a. without interference. After bolt 3 has expended its recoil movement over the surface 33 of hammer Iii it is returned to battery position by the slide 8 (Fig. 1), under bias of spring 34, one end of which abuts rear surface 35 of slide 8 and the other the front surface 33 of receiver 4. It is to be understood, however, that the forward end of bolt 3, during its counterrecoil movement strips the uppermost cartridge from the ammunition magazine 4a (Fig. 2) located in housing 4 and forces it forward into the chamber of the barrel 2, in a manner commonly known to those familiar with the art. The bolt, after havin reached battery position is rotated and locked by the rearwardly projecting handle 9 against the base of a cartridge. As the bolt 3, in its counterrecoil movement leaves the top surface 33 of hammer In (Fig. 5) the hammer is released and commences a counter-clockwise movement on its axial pin l2. However, the movement is soon checked by sear H, the nose- 29 of which has been forced into notch 28a of hammer H] by spring 2| during recoil movement of bolt 3. Since the bias of spring i4 against hammer I6 is greater than bias of spring 21 against sear l'i, nose 29 of sear I1 is forced upwardly and rearwardly by the added leverage of lower part of hammer Hi, until the surface 31 of scar l'i abuts surface 33 of projection 39 of trigger 55. It will be noted that this rearward movement of scar i1 is possible because of the ability of sear I! to float, to-and-fro within the confines of the elongated hole 29. In Fig. 5, it will be noted that sear ll, wedged between notch 28a of hammer Ii] and abutment 38 of projection 39 of trigger I6 has prevented the release of hammer Ill even while the trigger 16 had once been pulled and is still in the pulled position and it is impossible for the hammer ill to be dislodged from its cool-ted position. However, upon releasing trigger It (Fig. 6), the continued pressure of bottom portion of hammer in against nose 29 of scar ll forces the sear still farther to the rear compelling the surface 31 to slip over the abutment 38 of projection 39 of trigger l6 and come to rest on top surface 40 of abutment 39. It is pointed out that this slippage occurs as soon as trigger i5 is released and heel 26 comes to rest on seat 21 of housing 4. Therefore, in order to release hammer 13 it will only be necessary to re-pull the trigger l6 and projection 39 thereof will lift the rear end 40 of sear i'i, forcing the nose 29 of the sear I? out of hammer notch 28a allowing it to swing in a counterclockwise movement on transverse pin 2 to strike the firing pin in the bolt and fire the cartridge in the chamber. It will also be noted that on the initial pull of the trigger, the hammer IEI was released and after firing the cartridge, bolt 3 recoiled to the rear, cocked hammer ii} during recoil and even though trigger it might have continued to be held in the pulled position it was unable to effect continuous fire and the only manner in which continuous fire could be accomplished is by release of trigger it completely and re-pull it. However, such action would not produce continuous automatic action as it is apparent that only one shot could be fired at each pull of the trigger.

In order to provide fully-automatic action for this type of mechanism I provide a means to enable the slide 8, through a system of selective controls to release hammer i 5 only after the bolt 3 had reached its locked battery position and not sooner, and repeat this action as long as the trigger is held in pulled position. I accomplish this in a very simple manner doing so without disturbing the functions of the various existing parts of the mechanism and in a manner which pro vides for full and positive control of the firing of the firearm by the trigger, in either semi-autom-atic or fully-automatic functioning at the will of the firer.

In Fig. 7 is shown a fragmentary cross-section of a mechanism for controlling the hammer and sear by means of the trigger, in a U. carbine, caliber .30 Ml. It will be readily seen that trigger I6 is in pulled position and bolt 3 in locked battery position. It will also be noted than even through trigger I6 is in the pulled position, the hammer l0 remains in a cooked position, for reasons previously explained. With trigger I6 and sear I! being in the positions shown, it is obvious that the only manner in which hammer It may be released is by providing a supplementary member to depress the nose 29 of sear l1 from the notch 28a of hammer I0. such a supplementary member (Fig. 9) which I call the sear trigger 42, with a downwardly projecting sear engaging nose 43 at its frontend and a downwardly projecting trigger engaging foot 44 and an upwardly extending actuating projection 45 at the rear end. Sear tripper 42 (Fig. 13) is pivotally mounted on pin 46 extending through hole 46a in the sear tripper and hole 461) on bracket 41. Bracket 41 is secured to trigger housing 4 by a headed screw 48 in hole 48a. Headed screw 48 now replaces the pin I2 used in the basic assembly. A locating hole 49 is also provided in bracket 4'! and serves to maintain alignment of the bracket on the housing 4 by utilizing the location of the pin I8 of the basic assembly which pin is now replaced by a similar pin 49a, the length of which has been increased by an amount equal to the thickness of the material from which bracket 4'! is fabricated.

Trigger engaging foot 44 of scar tripper 42 nor-' mally rests upon trigger projection 39 so when the trigger is pulled the sear tripper 42 and its actuating projection 45 are moved from a lowered inoperative position (Fig. 15) to a raised operative position (Fig. 16) Here I'desire to point out that in the design of all firearms, the relative positions of the vital parts of the mechanism such as the hammer, scar and trigger are fixed and their pivot centers never change for the reason that proper functioning of the firearm is dependent on the maintenance of these fixed positions so that the parts will cooperate with one another to produce positive and safe action of the mechanism. Therefore, I likewise have provided for utilizing the existing fixed centers of said vital components of the action for mounting the supplementary parts of the selective fire converter embodying my invention.

In Fig. 16 it will be seen that with sear-tripper 42' pivotally mounted on bracket 4'! it is possible to dislodge sear I! from its wedged-in position between hammer-notch 28a and abutment 38 of projection 39 of trigger [6 by merely imparting a forward movement to the actuating projection 45 of sear tripper 42. Such movement is produced by a third member in a manner to be explained later and it is obvious that such movement will cause sear engaging nose 43 to depress nose 29 of sear H from notch 28a of hammer ill and release the hammer so as to enable it to perform its firing function. To impart such a for- Ward movement I provide an actuator base 50 and extension 5| (Fig. 13), said extension having a downward projecting abutment 52 at the front end and a relieved surface 53 at its rear end. The front end of actuator 58 terminates in a tongue shaped projection 54 having formed therein an elongated hole 55. Actuator 50 and extension 5| are secured together by screw 56 passing through elongated hole 55 into extension 5!. It will be obvious that when the head of screw 56 is tightened against face of tongue 54 of the actuator 50 the two members will be securely held together as a single unit and the elongated hole becomes a means for adjusting the combined length of the actuator 50 and extension 5!. However, to prevent slippage between the two members I provide serrations 51 (Fig. 14) on the mating faces of the members and to assure alignment of the members I provide parallel guides 58 on the extension 5|, between which the tongue 51! is able to slide to-and-fro for adjustment purposes when screw 56 is loosened for that purpose.

Near the rear end of the actuating bar 50 (Fig.

I provide I 11) I provide an elongated hole 59 and near the front end a stud 60 securely anchored in actuator 50 so that a portion of it projects therefrom. I also provide a pawl 61 pivoted on a pin 62 which pawl is under bias of spring 63. The ends of pin 62 are peened over lightly (Fig. 12) to prevent the pawl SI and actuator 59 from becoming detached. It will be noted that nose 64 of pawl 6| is urged downwardly by spring 63 and its downward movement is limited by the stop 61a provided at the front end of the pawl. Thus, it will be obvious that the direction of movement of the pawl, from its static position, will be upward only and is unable to drop lower than the limit established by the stop 6Ia.

It Will also be noted that the component parts of the actuator bar 59 and extension when assembled as described, combine into a single unit and may be attached or detached from its mounting quite readily. For this reason, it will be quite obvious that sear tripper 42 even though remaining installed with bracket 41 on housing 4, will be unable to function the sear I1, without the aid of the actuator 59 and extension 5!, the functions of which will be described later.

For the purpose of positioning the actuator 59 to obtain the desired type of operation (semiautomatic or fully-automatic), I provide a selector lever 65 (Fig. 10) having therein a hole 66 and a cam-like slot 68. A projection 69 at its upper end contains rigidly secured thereto a knurled projecting handle 10. A projection H at its lower end terminates in a convex surface 12. It will be understood that lever 65 is to be fabricated from a springlike material having flexing qualities, so that the convex surface portion 12 of projection H is able to flex sidewise for the purpose to be explained later.

I also provide a mounting plate 13 (Fig. 10) having a hole 74 therein and upper and lower radially disposed detent surfaces 15 in its outer face. I also provide a pin 16 having reduced diameter 15 on which I mount the plate 13 and lever 65 as a single unit, the pin 16 of which projects inwardly and is utilized to substitute for the headed transverse pin 1 used in the basic assembly to secure housing 4 to receiver I. In Fig. 13 is shown the manner in which the unit comprising lever 65, mounting plate 13 and pin 16 are employed. However, I wish to point out that in assembling these components, while the end of the reduced diameter 15 of pin 16 is peened over to retain the members, such peening operation is not so severe as to effect clamping action and thus hinder rotation of the parts on the pin. It will be seen that when the unit is installed (Fig. 13), the parallel edges 13a of the mounting plate 13 abut coinciding parallel edges 131) (Fig. '7) of recess 4a in housing 4 and is secured in this manner. Therefore, it will be obviously noted that when lever 65 (Fig. 13) is rotated clockwise or counter-clockwise, the mounting plate 13 will be retained in a fixed position and as the convex surface 12 on the projection ll of lever 65 assumes its position over either the upper or lower detents 75, said convex surface will readily snap into place in the detent and retain the lever 65 in either a forward position or rearward position as may be desired, (forward full-automatic, rearward semi-automatic).

It is to be understood that the components combining lever 65, mounting plate 73 and pin 16 when assembled as described comprise a single unit, likewise, the components combining the bracket d1, stud 41a and sear tripper 42 will comprise a single unit and still, actuator 50, extension 5| and pawl 6| another unit, and in operation these units function in combination with existing units of the firearm in the following manner:

In Fig. 13 it will be seen that bracket 41, having pivoted thereto sear tripper 42, is secured to the housing 4 by the screw 43 as previously described. A selecting mechanism combining the lever 65, mounting plate 13 and pin 16 is installed so that the pin 76 will now replace the headed pin I of the basic assembly which was utilized for securing housing 4 to receiver I as previously explained. The actuator 50, extension 51, pawl 5| also comprising a single unit is mounted at the rear by placing the elongated hole 59 in actuator over stud 41a projecting from bracket 41. The front end of actuator 59 is suspended by passing the stud 60 of actuator 50 through the elongated hole 68 of the lever 65 in a manner clearly illustrated in the drawings.

With the various units installed as described, if it should be desired that the firearm be capable of delivering full-automatic fire, the lever 65 is moved counter-clockwise by pressing forward on stud 10 until a distinct click sound is heard which indicates that the convex surface 12 on projection H of lever had snapped into position in the upper detent 15 of mounting plate 13. In moving the lever 65 to this position, the elongated hole 68 in lever cams the actuator extension downward so that in this position the actuator 50 and the extension 5! are horizontally disposed on the side of the firearm and downward projecting abut ment 52 will contact front face 801 of the slide 8. Likewise, if the selector lever 55 is moved clockwise or in a rearwardly direction the elongated hole 68 will be forced in upward direction acting on the stud 60 in front and pivoting on the stud a in bracket 47 at the rear, thus raising said actuator so that the downward projecting abutment 52 is raised above the uppermost surface 8b of the slide 8. It will be clearly seen that with the lever in this position it becomes secured by the convex surface 12 engaging the lower detent T5 in the mounting plate 13. It will also be seen that slide 8 during counterrecoil is unable to come into contact with the downward projecting abutment 52 of the extension 5| because it has been raised to a height sufiicient to avoid contact.

It will be noted that upon recoil of slide 8, the.

rear face comes into contact with the front edge 50a of actuator 50 and forces it in a rearward direction, to the maximum limits of the end 5911 of the elongated hole 59. It will also be noted that the nose 64 of pawl 6| will also move rearwardly over the vertical projection of the seartripper 42 and should, during counter-recoil of bolt, the vertical projection 45 at this moment he in a raised position (Fig. 16) and the lever 65 adjusted so that it will allow the downward projecting abutment 52 to come into contact with the front face 8a of the slide 8, the nose B4 of pawl Bl will contact the actuating projection 45 of the sear tripper 42 and cause its sear engaging nose 43 to force the nose 29 of the sear from the notch 28a of hammer I0 allowing it to function and continue firingv until the trigger is released and the actuator projection 45 of the sear-tripper 42 drops from its raised operative position to its lowered inoperative position with the projection 39 of the trigger I6 as it comes to rest on its seat 2 1 of housing 4, at which time it will be impossible for the nose 64 of pawl 6| to contact the vertical projection 45 of sear-tripper 42 and firing will cease with a loaded cartridge remaining in the chamber. If it is desired to resume firing it will be only necessary to pull trigger l6 again and firing will be resumed, for the spring 63 of the pawl will be overcome by the upward movement of the vertical projection 45 of sear-tripper 42 and permit the trigger to operate the sear ll in a normal manner, at the same time raising the vertical projection 45 of sear-tripper A2 to its functioning position.

It will be understood, however, that when firing is suspended by the release of the trigger, the action may be locked to prevent pulling the trigger and causing accidental discharge of the firearm, since the basic safety mechanism of the firearm has remained unchanged by the supplementary component parts of my invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the scar, and an automatically operated reciprocable slide movable from and to a battery position to cock the hammer following each discharge; a selective fire converter comprising a bracket on one side of the firearm adjacent the trigger and sear, a sear tripper pivoted on said bracket and arranged to move the sear for disengaging it from the hammer, said sear tripper being movable from inoperative to operative position by pulling the trigger, and a slidable actuator bar reciprocable along one side of the firearm relative to said bracket by reciprocation of the slide, said actuator bar engaging and moving said sear tripper, when in operative position, during reciprocation to disengage the sear from the hammer.

2. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the scar, and an automatically operated reciprocable slide movable from and to a battery position to cock the hammer following each discharge; a selective fire converter comprising a bracket on one side of the firearm adjacent the trigger and sear, a scar tripper pivoted on said bracket and arranged to move the sear for disengaging it from the hammer, said sear tripper being movable from inoperative to operative position by pulling the trigger, a slidable actuator bar reciprocable along one side of the firearm relative to said bracket by reciprocation of the slide, said actuator bar engaging and moving said sear tripper, when in operative position, during reciprocation to disengage the sear from the hammer, and means including a shiftable selector lever engageable with said actuator bar for rendering said actuator bar inoperative.

3. In an automatic firearm having a hammer, asear for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically'operated reciprocable Slide movable from and to a battery position to cock the hammer following each discharge; a selective tripper being movable from inoperativeto operative position by pulling the trigger, a slidable actuator bar reciprocable along one side of the firearm by reciprocation of the slide, and a pawl pivoted on the rear end of said bar to override said sear tripper when in'its operative position during rearward movement of said bar but to engage and move said sear tripper during forward movement of the bar thereby disengaging the sear from the hammer.

4. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the scar, and an automatically operated reciprocable slide movable from and to a battery position to cock the hammer following each discharge; a selective fire converter comprising a bracket on one side of the firearm adjacent the trigger and sear, a scar tripper pivoted on the bracket above the trigger, an actuating projection on said sear tripper, a downwardly extending trigger engaging foot on the rearward end of said sear tripper movable by pulling the trigger to shift said actuating projection from inoperative to operative position, a scar engaging nose on the forward end of said sear tripper, and a slidable actuator bar reciprocable along one side of the firearm relative to said bracket by reciprocation of the slide, said actuator bar engaging and moving said actuating projection on said sear tripper, when in its operative position, thereby causing said sear engaging nose to release the sear from the hammer.

5. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide movable from and to a battery position to cock the hammer following each discharge; a selective fire converter comprising a bracket on one side of the firearm adjacent the trigger and sear, a sear tripper pivoted on the bracket above the trigger, an actuating projection on said sear tripper, a downwardly extending trigger engaging foot on the rearward end of said sear tripper movable by pulling the trigger to shift said actuating projection from inoperative to operative position, a scar engaging nose on the forward end of said sear tripper, a slidable actuator bar reciprocable along one side of the firearm relative to said bracket by reciprocation of the slide, and a pawl on the rearward end of said bar pivoted to override said actuating projection during rearward movement of said bar but to engage and move said actuating projection upon forward movement of the bar and thereby cause said sear engaging nose to release the sear from the hammer.

6. In an automatic firearm having a hammer, a scar for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective fire converter comprising a slidable actuator bar reciprocable along one side of the firearm by reciprocation of the slide, said actuator bar extending rearwardly of the firearm above the trigger, and a sear tripper pivoted above the trigger and movable by the trigger from an inoperative position displaced from the path of reciprocation of said actuator bar to an operative position in the path of said actuator bar, said sear tripper being arranged to engage and move the sear to release the hammer upon being engaged and moved by said actuator bar.

'7. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the scar, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective fire converter comprising a sear tripper pivoted in dependently of the trigger, a slidable actuator bar along one side of the firearm, spaced abutments on the forward portion of said bar arranged in the path of said slide to be engaged by the front and back edges thereof when the slide reciprocates to thereby reciprocate said bar, and a projection on said bar engageable with said sear tripper for operating it upon reciprocation of said bar by the slide.

8. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective fire converter comprising a sear tripper pivoted independently of the trigger and arranged to move the sear for disengaging it from the hammer, a slidable actuator bar along one side of the firearm, a first abutment at the forward end of said bar engaged by the forward end of the slide, a second abutment on an intermediate portion of said bar engage-d by the rear end of said slide when moved to recoil position, and a projection on the rear end of said bar engaging and operating said sear tripper upon reciprocation of said bar by engagement of the slide with said abutments.

9. In a selective fire converter for an automatic firearm having a hammer, a sear for retaining the hammer in'cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide; a selective fire converter comprising a bracket attachable by existing transverse pins to one side of the firearm, a sear tripper pivoted on said bracket, a slide operated bar reciprocable on one side of the firearm, an actuating projection on said sear tripper adapted to be engaged and moved bysaid bar, a trigger engaging portion on said sear tripper arranged to be moved by pulling the trigger to shift said actuating projection from an inoperative position displaced from the path of reciprocation of the bar to an operative position in the path of reciprocation of the bar, and a sear engaging portion on said sear tripper movable upon engagement of the bar with said actuating projection for engaging and moving the sear to release the hammer.

10. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective'fire converter comprising a slidable actuator bar reciprocable along one side of the firearm by reciprocation of the slide, a pawl pivoted on said actuator bar above the trigger, and a sear tripper pivoted above the trigger, said pawl moving to override said sear tripper upon rearward movement of said actuator bar but engaging and moving said sear tripper upon forward movement of said actuator bar, said sear tripper being arranged to engage and move the sear to release the hammer upon being engaged and moved-by said pawl.

11. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the sear, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective fire converter comprising a sear tripper pivoted independently of the trigger, a slidable actuator bar along one side of the firearm, spaced abutments on the forward portion of said bar arranged in the path of said slide to be engaged by the front and back edges thereof when the slide reciprocates to thereby reciprocate said bar, a projection on said bar engageable with said sear tripper for operating it upon reciprocation of said bar by said slide and means including a shiftable selector lever operatively connected with said bar for moving said projection toward and from the path of reciprocation of said bar.

12. In an automatic firearm having a hammer, a sear for retaining the hammer in cocked position, a trigger for disengaging the scar, and an automatically operated reciprocable slide movable from and to a battery position to cook the hammer following each discharge; a selective fire converter comprising a sear tripper pivoted independently of the trigger and arranged to move the sear for disengaging it from the hammer, a slidable actuator bar along one side of the firearm, a first abutment at the forward end of said bar engaged by the forward end of the slide, a second abutment on an intermediate portion of said bar engaged by the rear end of said slide when moved to recoil position, and a pawl pivoted on the rearward end of said bar, said pawl moving to override said sear tripper upon rearward movement of said bar but engaging and moving said sear tripper upon forward movement of said bar.

13. An automatic firearm including a receiver, an automatically reciprocating slide on said receiver, a trigger housing on said receiver, a hammer pin extending transversely through said housing, a hammer pivoted on said hammer pin, a trigger pin extending transversely through said housing, a trigger pivoted on said trigger pin, and a scar floating on said trigger pin; in combination with a selective fire converter comprising a bracket secured on one side of said trigger housing by at least one of said pins, a pivotally mounted sear tripper, an actuator bar reciprocably mounted along one side of said receiver, a pawl on the rearward end of said bar, spaced abutments on the forward end of said bar to engage said slide and thereby reciprocate said bar, an actuating projection on the upper part of said sear tripper engageable by said pawl, and a sear engaging portion on said sear tripper for engaging and moving the sear to release the hammer upon operation of said sear tripper by said pawl.

ALONZO F. 'GAIDOS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,342,824 Swebilius Feb. 29, 1944 2,383,487 Johnson Aug. 28, 1945 2,462,130 Rudd Feb 22,1949 2,465,487 Sampson et a1 Mar. 29, 1949 2,469,053 Roemer May 3, 1949 

